Robust electromagnetic absorption by graphene/polymer heterostructures

Abstract

Polymer/graphene heterostructures present good shielding efficiency against GHz electromagnetic perturbations. Theory and experiments demonstrate that there is an optimum number of graphene planes, separated by thin polymer spacers, leading to maximum absorption for millimeter waves Batrakov et al (2014 Sci. Rep. 4 7191). Here, electrodynamics of ideal polymer/graphene multilayered material is first approached with a well-adapted continued-fraction formalism. In a second stage, rigorous coupled wave analysis is used to account for the presence of defects in graphene that are typical of samples produced by chemical vapor deposition, namely microscopic holes, microscopic dots (embryos of a second layer) and grain boundaries. It is shown that the optimum absorbance of graphene/polymer multilayers does not weaken to the first order in defect concentration. This finding testifies to the robustness of the shielding efficiency of the proposed absorption device.

Efficiency enhancement of perovskite solar cells based on opal-like photonic crystals

“…Indeed, the Brewster angle prevents light reflection and consequently allows more light to be absorbed within the structure. This angular behaviour has been observed elsewhere [57]. Finally, the robustness of the designed PSC regarding angular dependence is confirmed since the reported iQE are all superior to 40% up to grazing incidence.…”

Modified Brewster angle on conducting 2D materials

“…To calculate the modified Brewster angle, the generalized reflection Fresnel coefficient in p-polarization should be canceled out once a 2D conducting plane is inserted between two semi-infinite dielectric media. Assuming that the 2D conducting layer is not charged, one obtains the reflectance [27,28,29]:…”

“…Modified Brewster angle on conducting 2D materials 2 Despite their vanishing thicknesses, some 2D materials interact strongly with light as exemplified by a single graphene layer, which is able to absorb 2.3% of incoming visible light [5] and 10 times more in the microwave range [6,7,8]. Moreover, 2D materials present a rich diversity of electronic structures.…”

Effect of graphene grains size on the microwave electromagnetic shielding effectiveness of graphene/polymer multilayers

“…This method is well adapted to plane-stratified systems with a periodic variation of dielectric permittivity in the lateral directions. 17,18 The frequency used in the calculations was 30 GHz (1 cm wavelength in vacuum), the PMMA/graphene multilayer was treated as a stack of dielectric slabs (PMMA spacers, 100 nm thick, permittivity at the working frequency of 2.6 18 ), alternating with graphene layers and deposited on a SiO 2 substrate with permittivity 3.7. 18 Each graphene layer was treated as ultra-thin conducting medium (thickness d graph = 0.34nm) with complex bulk dielectric function ǫ(ω) = 2.5 + i σ 2D ǫ 0 ωd graph .…”

“…Those results can be compared with those for a few percentages of small air holes in the graphene sheets that already proved not affecting the electromagnetic properties of graphene. 17 3 Experimental details…”